Repair limit policy of aircraft component based on extended uncertain random renewal reward process

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chunxiao Zhang ◽  
Xinwang Li ◽  
Xiaona Liu ◽  
Qiang Li ◽  
Yizhou Bai
Keyword(s):  
Programming Model ◽  
Civil Aviation ◽  
Maintenance Cost ◽  
Engineering Practice ◽  
Content Type ◽  
Limit Time ◽  
Aircraft Component ◽  
New Type ◽  
Reward Process ◽  
Renewal Reward Process

PurposeThe purpose of this paper is to focus on an optimizing maintenance policy with repair limit time for a new type of aircraft component, in which the lifetime is assumed to be an uncertain variable due to no historical operation data, and the repair time is a random variable that can be described by the experimental data.Design/methodology/approachTo describe this repair limit time policy over an infinite time horizon, an extended uncertain random renewal reward theorem is firstly proposed based on chance theory, involves uncertain random interarrival times and stochastic rewards. Accordingly, the uncertain random programming model, which minimized the expected maintenance cost rate, is formulated to find the optimal repair limit time.FindingsA numerical example with sensitivity analysis is provided to illustrate the utility of the proposed policy. It provides a useful reference and guidance for aircraft optimization. For maintainers, it plays an important guiding role in engineering practice.Originality/valueThe proposed uncertain random renewal reward process proved useful for the optimization of maintenance strategy with maintenance limited time for a new type of aircraft components, which provides scientific support for aircraft maintenance decision-making for civil aviation enterprises.

Expected maintenance waste reduction benefits after implementation of Just in Time (JIT) philosophy in maintenance (a statistical analysis)

2019 ◽  
Vol 25 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Sandeep Phogat ◽  
Anil Kumar Gupta
Keyword(s):  
Data Interpretation ◽  
General Information ◽  
Spare Parts ◽  
Waste Reduction ◽  
Maintenance Cost ◽  
Just In Time ◽  
Content Type ◽  
Great Saving ◽  
Research Findings ◽  
Structured Questionnaire

Purpose The maintenance department of today, like many other departments, is under sustained pressure to slash costs, show outcome and support the assignment of the organization, as it is a commonsensical prospect from the business perspective. The purpose of this paper is to examine expected maintenance waste reduction benefits in the maintenance of organizations after the implementation of just-in-time (JIT) managerial philosophy. For this, a structured questionnaire was designed and sent to the 421 industries in India. Design/methodology/approach The designed questionnaire was divided into two sections A and B to assist data interpretation. The aim of the section A was to build general information of participants, type of organization, number of employees, annual turnover of the organization, etc. Section B was also a structured questionnaire developed based on a five-point Likert scale. The identified critical elements of the JIT were included in the questionnaire to identify the maintenance waste reduction benefits in the maintenance of organizations. Findings On the basis of the 133 responses, hypothesis testing was done with the help of Z-test, and it was found out that in maintenance, we can reduce a large inventory of spare parts and also shorten the excessive maintenance activities due to the implementation of JIT philosophy. All the four wastes: waste of processing; waste of rejects/rework/scrap in case of poor maintenance; waste of the transport of spares, and waste of motion, have approximately equal weightage in their reduction. Waste of waiting for spares got the last rank, which showed that there are little bit chances in the reduction of waiting for spares after the implementation of JIT philosophy in maintenance. Practical implications The implication of the research findings for maintenance of organizations is that if maintenance practitioners implement elements of JIT philosophy in maintenance then there will be a great reduction in the maintenance wastes. Originality/value This paper will be abundantly useful for the maintenance professionals, researchers and others concerned with maintenance to understand the significance of JIT philosophy implementation to get the expected reduction benefits in maintenance wastes of organizations which will be helpful in the great saving of maintenance cost and time side by side great increment in the availability of machines.

Sublimation of composite ice and its influence on performance of ice shells

2021 ◽  
Vol 36 (1) ◽  
pp. 67-77
Author(s):  
Yue Wu ◽  
Junkai Huang ◽  
Jiafeng Chen
Keyword(s):  
Numerical Simulation ◽  
Shell Structure ◽  
Composite Shell ◽  
Engineering Practice ◽  
Sublimation Rate ◽  
Long Span ◽  
Static Performance ◽  
New Type ◽  
Ice Sublimation ◽  
Composite Shell Structure

The long-span ice composite shell structure is a new type of ice and snow structure developed in recent years. The engineering practice of ice composite shell shows that sublimation is one of the important reasons for its damage and even collapse. In this paper, we firstly supplemented the existing H-K equation and obtained the revised ice sublimation equation through indoor evaporative plate experiment considering the influence of admixtures and wind speed. Afterwards, combining the simulations of solar radiation and CFD, the numerical simulation of sublimation distribution on the surface of were realized by programming in Grasshopper platform. During sublimation, the thickness of the ice composite shell decreases by 0.38 mm every 10 days and the sublimation rate on the sunny side was 1.7 times that on the shady side. Finally, the static performance and stability of the sublimated ice composite spherical shell were analyzed. After 70 days of sublimation, the thickness of the ice composite shell structure becomes thinner and uneven, which leads its sensitivity to external load increases.

Toward a theory on workplaces for smart workers

Facilities ◽  
2019 ◽  
Vol 38 (3/4) ◽  
pp. 298-315
Author(s):  
Luisa Errichiello ◽  
Tommasina Pianese
Keyword(s):  
Web Sites ◽  
Participant Observation ◽  
Secondary Data ◽  
Primary Data ◽  
Innovative Design ◽  
Content Type ◽  
New Type ◽  
Smart Working ◽  
Research Propositions

Purpose The purpose of this paper is to identify the main features of smart work centers (SWCs) and show how these innovative offices would support the implementation of smart working and related changes in workspaces (“bricks”), technologies (“bytes”) and organizational practices (“behaviors”). Design/methodology/approach In this study, scientific literature is combined with white papers and business reports and visits to 14 workplaces, including offices designed as SWCs, co-working spaces, one telecenter, one accelerator and one fab lab. Primary data were collected through interviews with managers and users and non-participant observation, whereas secondary data included web-sites, brochures, presentations, press releases and official documents. Findings The authors developed research propositions about how the design of spaces and the availability of technology within SWCs would support the “bricks” and “bytes” levers of smart working. More importantly, the authors assumed that this new type of workplace would sustain changes in employees’ behaviors and managers’ practices, thus helping to overcome several challenges traditionally associated with remote working. Research limitations/implications The exploratory nature of the research only provides preliminary information about the role of SWCs within smart working programs. Additional qualitative and quantitative empirical investigation is required. Practical implications This study provides valuable knowledge about how the design of corporate offices can be leveraged to sustain the implementation of smart working. Originality/value This study advances knowledge on workplaces by focusing on an innovative design of traditional offices (SWC). It also lays the foundations for future investigation aimed at testing the developed propositions.

scholarly journals Location of regional and international hub ports in liner shipping

2017 ◽  
Vol 2 (2) ◽  
pp. 114-125 ◽  
Author(s):  
Jianfeng Zheng ◽  
Cong Fu ◽  
Haibo Kuang
Keyword(s):  
Design Methodology ◽  
Location Problem ◽  
Programming Model ◽  
Liner Shipping ◽  
Mixed Integer ◽  
Eastern Asia ◽  
Hub Location ◽  
Hub Location Problem ◽  
Content Type ◽  
Western Asia

Purpose This paper aims to investigate the location of regional and international hub ports in liner shipping by proposing a hierarchical hub location problem. Design/methodology/approach This paper develops a mixed-integer linear programming model for the authors’ proposed problem. Numerical experiments based on a realistic Asia-Europe-Oceania liner shipping network are carried out to account for the effectiveness of this model. Findings The results show that one international hub port (i.e. Rotterdam) and one regional hub port (i.e. Zeebrugge) are opened in Europe. Two international hub ports (i.e. Sokhna and Salalah) are located in Western Asia, where no regional hub port is established. One international hub port (i.e. Colombo) and one regional hub port (i.e. Cochin) are opened in Southern Asia. One international hub port (i.e. Singapore) and one regional hub port (i.e. Jakarta) are opened in Southeastern Asia and Australia. Three international hub ports (i.e. Hong Kong, Shanghai and Yokohama) and two regional hub ports (i.e. Qingdao and Kwangyang) are opened in Eastern Asia. Originality/value This paper proposes a hierarchical hub location problem, in which the authors distinguish between regional and international hub ports in liner shipping. Moreover, scale economies in ship size are considered. Furthermore, the proposed problem introduces the main ports.

The operational efficiency of passenger aircraft

2006 ◽  
Vol 78 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Donald McLean
Keyword(s):  
Design Methodology ◽  
Operational Efficiency ◽  
Civil Aviation ◽  
Content Type ◽  
Transport Economics ◽  
Load Factors ◽  
Consistent Assessment ◽  
Definition Of ◽  
Passenger Aircraft ◽  
Practical Implications

PurposeTo provide for the use of airlines and other civil aviation organizations a practical definition of operational efficiency and to show how it can be determined.Design/methodology/approachA brief account of air transport economics is used to demonstrate how bom load factors and aircraft utilization need to be considered in assessing operational efficiency. Then other efficiencies are treated briefly before an example is given of how the better of two fictitious aircraft can be chosen for a particular route. A second example involving the calculation of the operational efficiency achieved by an imaginary airline is also given to show that the typical value is lower than might be expected, particularly in view of the relatively high load factors involved.FindingsProvides performance values and economic figures which are typical of current airline operations.Practical implicationsUse of the proposed definition will allow the consistent assessment of the economic performance of airlines.Originality/valueAt present there is no definition of operational efficiency in general use although it is greatly needed by airlines. The definition proposed in this paper is practical and easy to use.

Passenger aircraft emissions analysis at Ordu-Giresun International Airport, Turkey in 2017

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ilkay Orhan
Keyword(s):  
Aircraft Engine ◽  
Civil Aviation ◽  
Exhaust Emission ◽  
Aircraft Emissions ◽  
Emission Data ◽  
Emission Analysis ◽  
Content Type ◽  
International Airport ◽  
Engine Emission ◽  
The Impact

Purpose The purpose of this study is to present the pollutant gas produced by hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) and the quantity of fuel burned from commercial aircraft at Ordu-Giresun International Airport, Turkey during the landing and take-off (LTO) cycles in 2017. Design/methodology/approach The flight data recorded by the General Directorate of State Airports Authority and the aircraft engine emission data from International Civil Aviation Organization (ICAO) Engine Exhaust Emission Databank were used for calculation. The aircraft and engine types used by the airlines for flight at Ordu-Giresun International Airport were determined. To evaluate the effect of taxi time on emission amounts, analysis and evaluations were made by taking different taxi times into consideration. Findings As a result of the emission analysis, the amount of fuel consumed by the aircraft were calculated as 6,551.52 t/y, and the emission amounts for CO, HC and NOx were estimated as 66.81, 4.20 and 79.97 t/y, respectively. Practical implications This study is aimed to reveal the effect and contribution of taxi time on the emitted emission at the airport during the LTO phase of the aircraft. Originality/value This study helps aviation authorities explain the importance of developing procedures that ensure the delivery of aircraft to flights in minimum time by raising awareness of the impact of taxi time on emitted emissions, and contributes to the determination of an aircraft emission inventory at Ordu-Giresun International Airport.

Modeling and scheduling hybrid open shops for makespan minimization

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kennedy Anderson Guimarães de Araújo ◽  
Tiberius Oliveira e Bonates ◽  
Bruno de Athayde Prata
Keyword(s):  
Programming Model ◽  
Computing Time ◽  
Iterated Local Search ◽  
Mixed Integer ◽  
Scheduling Problems ◽  
Priority Rules ◽  
Production Flow ◽  
Solution Quality ◽  
Content Type ◽  
Constructive Heuristics

Purpose This study aims to address the hybrid open shop problem (HOSP) with respect to the minimization of the overall finishing time or makespan. In the HOSP, we have to process n jobs in stages without preemption. Each job must be processed once in every stage, there is a set of mk identical machines in stage k and the production flow is immaterial. Design/methodology/approach Computational experiments carried out on a set of randomly generated instances showed that the minimal idleness heuristic (MIH) priority rule outperforms the longest processing time (LPT) rule proposed in the literature and the other proposed constructive methods on most instances. Findings The proposed mathematical model outperformed the existing model in the literature with respect to computing time, for small-sized instances, and solution quality within a time limit, for medium- and large-sized instances. The authors’ hybrid iterated local search (ILS) improved the solutions of the MIH rule, drastically outperforming the models on large-sized instances with respect to solution quality. Originality/value The authors formalize the HOSP, as well as argue its NP-hardness, and propose a mixed integer linear programming model to solve it. The authors propose several priority rules – constructive heuristics based on priority measures – for finding feasible solutions for the problem, consisting of adaptations of classical priority rules for scheduling problems. The authors also propose a hybrid ILS for improving the priority rules solutions.

scholarly journals Establishment and Application of Rapid Diagnosis for Reverse Transcription-Quantitative PCR of Newly Emerging Goose-Origin Nephrotic Astrovirus in China

mSphere ◽  
2018 ◽  
Vol 3 (6) ◽  
Author(s):  
Xiaoyuan Yuan ◽  
Kai Meng ◽  
Yuxia Zhang ◽  
Lihong Qi ◽  
Wu Ai ◽  
...  
Keyword(s):  
Quantitative Pcr ◽  
Clinical Application ◽  
Reverse Transcription ◽  
Test Sample ◽  
Sensitivity Testing ◽  
Content Type ◽  
Reverse Transcription Quantitative Pcr ◽  
Emerging Virus ◽  
New Type ◽  
And Control

ABSTRACT In 2017, a new type of goose-origin astrovirus (GoAstV) that is completely different from previously identified avian astroviruses (which have only 30.0% to 50.5% homology with GoAstV) has been isolated from diseased geese in China. This disease can cause joint swelling in sick geese, and the anatomy shows a clear precipitation of urate in the kidney. The rate of death and culling can reach more than 30%, revealing the disease’s severe pathogenicity. To quickly and accurately diagnose the newly emerging disease, we established a highly specific reverse transcription-quantitative PCR (RT-qPCR) method of detecting GoAstV. Sensitivity testing showed that the minimum amount of test sample for this method is 52.5 copies/μl. Clinical application confirmed that this method can quickly and effectively detect GoAstV, providing a diagnostic platform for the prevention and control of goose disease. IMPORTANCE Goose-origin astrovirus (GoAstV), as a newly emerging virus in 2017, is different from previously known astroviruses in the genus Avastrovirus. So far, few studies have focused on the novel virus. Considering the infectious development of astrovirus (AstV), we established a reverse transcription-quantitative PCR (RT-qPCR) assay with a strong specificity to quickly and accurately diagnose GoAstV. Confirmed by clinical application, this method can quickly and accurately detect prevalent GoAstV. The assay is thus convenient for clinical operation and is applicable to the monitoring of GoAstV disease.

scholarly journals The density of a passage time for a renewal-reward process perturbed by a diffusion

2013 ◽  
Vol 26 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Christophette Blanchet-Scalliet ◽  
Diana Dorobantu ◽  
Didier Rullière
Keyword(s):  
Passage Time ◽  
Reward Process ◽  
Renewal Reward Process

scholarly journals A Bacterial Microcompartment Is Used for Choline Fermentation byEscherichia coli536

2018 ◽  
Vol 200 (10) ◽  
Author(s):  
Taylor I. Herring ◽  
Tiffany N. Harris ◽  
Chiranjit Chowdhury ◽  
Sujit Kumar Mohanty ◽  
Thomas A. Bobik
Keyword(s):  
Electron Microscopy ◽  
Heart Disease ◽  
Gene Cluster ◽  
Transcriptional Regulator ◽  
Human Gut ◽  
Content Type ◽  
E Coli ◽  
Bacterial Microcompartment ◽  
New Type ◽  
Insight Into

ABSTRACTBacterial choline degradation in the human gut has been associated with cancer and heart disease. In addition, recent studies found that a bacterial microcompartment is involved in choline utilization byProteusandDesulfovibriospecies. However, many aspects of this process have not been fully defined. Here, we investigate choline degradation by the uropathogenEscherichia coli536. Growth studies indicatedE. coli536 degrades choline primarily by fermentation. Electron microscopy indicated that a bacterial microcompartment was used for this process. Bioinformatic analyses suggested that the choline utilization (cut) gene cluster ofE. coli536 includes two operons, one containing three genes and a main operon of 13 genes. Regulatory studies indicate that thecutXgene encodes a positive transcriptional regulator required for induction of the maincutoperon in response to choline supplementation. Each of the 16 genes in thecutcluster was individually deleted, and phenotypes were examined. ThecutX,cutY,cutF,cutO,cutC,cutD,cutU, andcutVgenes were required for choline degradation, but the remaining genes of thecutcluster were not essential under the conditions used. The reasons for these varied phenotypes are discussed.IMPORTANCEHere, we investigate choline degradation inE. coli536. These studies provide a basis for understanding a new type of bacterial microcompartment and may provide deeper insight into the link between choline degradation in the human gut and cancer and heart disease. These are also the first studies of choline degradation inE. coli536, an organism for which sophisticated genetic analysis methods are available. In addition, thecutgene cluster ofE. coli536 is located in pathogenicity island II (PAI-II536) and hence might contribute to pathogenesis.

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